because, due to
This structure provides a reason or explanation for something, expressed respectfully.
例句
お身体が弱いので、特別なケアが必要です。
Because your body is weak, special care is needed.
お話するのが楽しみなので、また来てください。
Because I look forward to talking with you, please come again.
食事の準備があるので、少し待ってください。
Because I am preparing a meal, please wait a moment.
快速测验
因为身体虚弱___，需要特别护理。